Once the current works are completed to the west of the terminal (which are small scale) the next area for expansion will be to the east of the terminal building. This will require partial infilling of the KGV dock (the water area right behind the terminal's baggage delivery doors, which wayward bags have been known to drop into from the carts on occasion !), and there will be space there for bigger stands nice and close to the terminal.
A parallel taxiway would require a lot more infilling of this dock.
Given that the current stands were sized for Dash-7s it's quite some skill that gets aircraft like 146s onto them.